When Adam is playing "Pong" on the Atari 2600, he's using a joystick. "Pong" was played with paddles.
Barry says he is going to mow lawns but his lawn tractor has no mowing deck on it.
Even though this is set on Thanksgiving in Philadelphia, several scenes occur outdoors, where the weather is apparently warm, the grass bright green, and the trees with full green foliage.
Barry's pager is a pager from the '80s. Only info you get on those is a phone number. When he gets messages on it in the show, he acts like he immediately knows who is contacting him and why without first calling the number back which is how it actually worked back then.
The FBI Warning on the Jazzercise video that Beverly puts into the VCR is the one used by The Walt Disney Company during the early to mid 2000s.